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Biomedical subjects

J C de la Macorra

Publications and source records attributed to J C de la Macorra.

11 recordsLinked to original sources
PubMed2004

Accuracy of the Justy II Apex locator in determining working length in simulated horizontal and vertical fractures.

AIM: To study the effectiveness of an electronic apex locator (EAL; Justy II; Yoshida Dentcraft, Tokyo, Japan) in locating simulated horizontal and vertical fractures in single roots. METHODOLOGY: An EAL was used to measure the distance within the canal of horizontal (n = 31) and vertical (n = 31) fractures, created with a disk in single-rooted teeth. Accuracy of the EAL was evaluated by comparing the measurements with those made using a size 10 file. Data were analysed with the non-parametric Passing and Bablok method. RESULTS: For simulated horizontal fractures, the EAL measured exactly the same length as a size 10 file, without constant or proportional errors. In vertical simulated fractures, the EAL measured (on average) with a constant error of 7.5 mm shorter than the size 10 file; the difference had a wide confidence interval (-72.3 to 2.6 mm). CONCLUSIONS: In this laboratory study, the Justy II EAL was able to determine accurately the position of simulated horizontal fractures, but was unreliable when measuring simulated vertical fractures.

Dental Instruments↗
PubMed2001

Sealing and dentin bond strength of adhesive systems in selected areas of perfused teeth.

OBJECTIVES: (1) Test the sealing capacity and tensile strength of various adhesive systems: Scotch Bond 1 (Single Bond in USA)(SB1)+Z100, Syntac Sprint (SYN)+Tetric Ceram, Prime and Bond 2.1 (PB21)+TPH Spectrum, F2000 (Adhesive+Compomer) (F2000) and Optibond Solo (OPT)+Prodigy, to perfused teeth (30 cm distilled H2O), in select areas. (2) Determine the relationship between sealing ability and size of adhesive area (BA) with tensile strength (TS). METHODS: Segments of human third molars (n=67) sealed with amalgam on their coronal side were connected to a perfusion system (30 cm distilled H2O), to measure the basal permeability. Access cavities were drilled through the amalgam to expose dentin (area range: 8.7-20.8 mm2) and measure the permeability of that area. Cavities were sealed with one of the test materials and permeability measured prior to tensile testing. The percentage of decrease in permeability (PPD) that occurred with the different combinations of materials was also measured. RESULTS. TENSILE STRENGTH: there were no statistically significant differences among groups. PERMEABILITY: ANOVA showed that there were statistically significant differences in the mean % decrease in permeability (PPD) among groups (p=0.018). Student-Newman-Keuls test (p<0.05) detected that the mean PPD of F2000 ranked statistically higher than that of SB1. Relationship among variables: a linear correlation was found defined by the formula TS=7.47+0.008 x PPD-0.23 x BA, with a significance of the model p=0.0097. SIGNIFICANCE: None of the materials studied reduced permeability up to 100%. They all produced low tensile bond strengths (maximum mean value of groups: 5.51 MPa (OPT)).

Acetone↗
PubMed2001

A predictive formula of the contraction stress in restorative and luting materials attending to free and adhered surfaces, volume and deformation.

OBJECTIVES: To find a predictive formula of stress, considering the surfaces (free, adhered) involved, the volume and characteristics of material and the deformation of the measuring system. MATERIALS AND METHODS: 231 samples of five chemically cured restoratives (Silar (SIL, 23), Clearfil F2 (CLE, 39), P10 (P10, 33), Concise (CON, 30), Isopast (ISO, 28)) and four luting (3M Experimental 241 (EXM, 20), Variolink II (VAR, 13), Vitremer LC (VTM, 20) and Dyract Cem (DYR, 25)) materials were allowed to polymerize until they reached a maximum tension (T(max), 25 min) between six pairs (null 5.81, 8.5, 11.26, 12.42, 17.02, 23.14 mm) of polished metallic discs (range of distances: 0.02-5.9 mm) mounted in a tension machine. The deformation of the measuring system was measured for the recorded forces. RESULTS: A descriptive non-linear formula T(max)=KVol(-3.267)FS(3.283)AS(0.642)Def(0.561) was found that individualizes the material's characteristics (K) that considers volume (Vol), free (FS) and adhered (AS) surfaces and deformation (Def) of the system for each force. This formula renders good correlation (material K (r(2) coefficient)): SIL 0.9998 (0.995), CLE 1.0062 (0.989), P10 1.0224 (0.990), CON 0.9908 (0.992), ISO 0.9648 (0.974), EXM 1.0083 (0.991), VAR 0.9777 (0.996), VTM 0.9925 (0.993), DYR 0.9971 (0.997) between actual T(max) and calculated Tension. There are statistically significant differences (p=0.002) between K values of both (restorative and luting) groups. SIGNIFICANCE: Predictive parameters have influence in a different way to what is actually considered, if the system is allowed to have deformation, as occurs naturally and volume and material's characteristics are considered.

Acrylic Resins↗
PubMed2001

Porosity of resin cements and resin-modified glass-ionomers.

PURPOSE: To quantify the internal free surface in various resin cements and glass-ionomer-based materials. MATERIALS AND METHODS: Materials tested were Nexus fluid (NXF) and viscous (NXV), Vitremer (VTM), Fuji II LC (FII), Vitremer Luting Cement (VLC), Dyract (DYR) and Compoglass (COM). Samples (n=5) were made of each material between two microscopic glass slides under same weight. With a transmitted light microscopy, four zones of each sample were evaluated, finding the number of porosities per mm2 (NP), the average radius of porosities (RP), the ratio of total area of surface porosities (micron2) to area (mm2) of specimen surface (TA) and the ratio of total volume of porosities (micron2) to area (mm2) of material surface (VP). RESULTS: Median test was used. NP: NXV, NXF and DYR had smaller NP than VTM and FII and (likely) than VLC (P> 0.0000001). RP was smaller for DYR than for VLC and (likely) than for NXV (P= 0.00019). TA: NXV, NXF and DYR had smaller TA than VTM, FII and VLC (P< 0.0000001). VP: NXV and DYR had smaller VP than FII and (likely) than VTM and VLC (P< 0.0000001).

Chi-Square Distribution↗
PubMed2000

Analysis of sealing vs tensile bond strength of eight adhesive restorative material systems.

PURPOSE: Using a simulated perfusion system, the intent was to determine: 1) the sealing ability of eight restorative materials (five composite resins and three compomers) used together with their corresponding dentin bonding systems, 2) their tensile bond strength, and 3) the correlation (if any) between both parameters. MATERIALS AND METHODS: Permeability in crown segments from sound human third molars (n = 140) subjected to simulated perfusion (32 cm of distilled water) was measured before and after restoring with each material, and the percentage of decrease in permeability (PPD) was recorded. Specimens were later subjected to tensile tests to determine the tensile bond strength (TBS) of the interface. Finally, parameters were analyzed for correlation. RESULTS: For the eight adhesive systems, the percentage of reduction in permeability was relatively high [mean in %, (SD)]: F2000 93.6 (5.7), SB1 88.6 (11.3), SSC 86.0 (5.7), PB20 81.1 (15.9), COM 77.5 (10.8), OPTS 75.3 (20.6), DYR 73.7 (12.7), SSPR 65.5 (19.8). TBS values were relatively low [mean (SD)], in MPa: F2000 1.8 (0.7), SB1 4.9 (1.4), SSC 2.6 (1.4), PB20 4.3 (1.2), COM 2.4 (1.1), OPTS 4.5 (1.7), DYR 1.6 (0.6), SSPR 4.2 (1.5). We could not demonstrate any statistically significant correlation between both parameters for these results (maximum significance [F2000]: r = 0.39, p = 0.206). CONCLUSION: No material completely ceased to filtrate through the interface. The low TBS values were probably due to the large size of adhesive areas. No significant correlation was found between PPD and TBS for the materials tested. There was a statistically significant relationship (r2 = 0.063, p = 0.018) between TBS and TBA (total bonded area), described by the equation TBS = 5.9 - 0.03.TBA.

Adhesives↗
PubMed1996

Quantification of the configuration factor in Class I and II cavities and simulated cervical erosions.

The configuration factor of adhesive cavities is defined as the ratio of the restoration's bonded to unbonded (free) surfaces. Such a configuration factor was described, on ideal cavities, as having a potential value in predicting the behaviour of the restorations, because it is related to the restoration's capacity for relieving stress by flow. The aim of this study was to measure the configuration factor value for real Class I and II cavities and simulated cervical erosions prepared in molars. Ten Class I, five Class II cavities and seven cervical erosions were analysed using a computerised digitising system. The configuration factor values found were 4.03 +/- 0.33 for Class I cavities, 1.85 +/- 0.59 for Class II cavities and 1.10 +/- 0.09 for simulated cervical erosions (P < 0.01).

Composite Resins↗
PubMed1987

Rokitansky's syndrome in association with reno-ureteral abnormalities. Teratogenic period.

A case of Rokitansky's syndrome in association with complete duplication of the right upper urinary tract is presented. From a chronological point of view, the morphogenetic processes of the urinary and genital tract are analyzed. It is supposed that the congenital abnormality is produced between the 30th and 37th day of gestation, because reno-ureteral duplication appears at 30-32 days and involution of the Müllerian structures appears at 37 days.

Abnormalities, Multiple↗
PubMedDate not supplied

Sealing and dentin bond strengths of adhesive systems.

The objectives of this research were (1) to analyze the variations of the permeability of dentin after restoration with two polyacid-modified resin composites (Compoglass, Dyract) and four single-bottle adhesives (Prime & Bond 2.0, Syntac Single Component, OptiBond Solo, and Single Bond--Scotch Bond 1 in Europe--immediately (approximately 1 hour) after insertion. A perfusion system with distilled water was used at a pressure of 32.5 cm of water; (2) to study the bond strength of their interfaces; and (3) to find the correlation, if any, between both parameters. None of the materials used produced a complete cessation in fluid filtration. Tensile bond strengths were very low (maximum: P&B = 3.96 MPa) probably because of the very large bonding surfaces used (mean bonded surface area = 88.8 mm2). No significant correlation was found between tensile bond strength and the sealing ability for any material.

Absorption↗